If I grab a Marth

[KoyalKitKat]

...what should I do? I'm quite a grab heavy character with peach and do pretty well with getting a grab. However I almost never know what I should with a Marth to reap some punishment. Would Sheik and Marth punishment off grab be the same. Any help for combos off off grab would be very helpful

 

[Sycorax]

Throwing him off stage is always nice. Edgeguarding Marth and/or putting him in a corner/on the ledge is a good way to rack up damage or even take a stock. Otherwise, dthrow dash attack works if they DI away, regrab/anir on bad DI. Uthrow nair/uair sometimes works, but I don't think it's supposed to. Uthrow platform tech chase also works.